CN107883082B - Threaded joint for oil well steel pipe - Google Patents
Threaded joint for oil well steel pipe Download PDFInfo
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- CN107883082B CN107883082B CN201710890006.4A CN201710890006A CN107883082B CN 107883082 B CN107883082 B CN 107883082B CN 201710890006 A CN201710890006 A CN 201710890006A CN 107883082 B CN107883082 B CN 107883082B
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- peripheral surface
- tank
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- 229910000831 Steel Inorganic materials 0.000 title claims abstract description 29
- 239000010959 steel Substances 0.000 title claims abstract description 29
- 239000003129 oil well Substances 0.000 title claims abstract description 17
- 230000002093 peripheral effect Effects 0.000 claims abstract description 49
- 238000007789 sealing Methods 0.000 claims abstract description 41
- 239000002184 metal Substances 0.000 claims description 20
- 239000012530 fluid Substances 0.000 claims description 7
- 230000006835 compression Effects 0.000 abstract description 27
- 238000007906 compression Methods 0.000 abstract description 27
- 239000003921 oil Substances 0.000 description 17
- 238000012360 testing method Methods 0.000 description 12
- 230000000052 comparative effect Effects 0.000 description 4
- 230000007423 decrease Effects 0.000 description 4
- 238000013461 design Methods 0.000 description 4
- 238000004519 manufacturing process Methods 0.000 description 4
- 230000003014 reinforcing effect Effects 0.000 description 4
- 238000009412 basement excavation Methods 0.000 description 2
- 238000011161 development Methods 0.000 description 2
- 238000011156 evaluation Methods 0.000 description 2
- 239000007789 gas Substances 0.000 description 2
- 230000014509 gene expression Effects 0.000 description 2
- VNWKTOKETHGBQD-UHFFFAOYSA-N methane Chemical compound C VNWKTOKETHGBQD-UHFFFAOYSA-N 0.000 description 2
- 238000005452 bending Methods 0.000 description 1
- 239000002131 composite material Substances 0.000 description 1
- 238000007796 conventional method Methods 0.000 description 1
- 230000008878 coupling Effects 0.000 description 1
- 238000010168 coupling process Methods 0.000 description 1
- 238000005859 coupling reaction Methods 0.000 description 1
- 239000010779 crude oil Substances 0.000 description 1
- 230000002950 deficient Effects 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 238000002474 experimental method Methods 0.000 description 1
- 238000003754 machining Methods 0.000 description 1
- 238000000034 method Methods 0.000 description 1
- 239000003345 natural gas Substances 0.000 description 1
- 239000003208 petroleum Substances 0.000 description 1
- 239000002436 steel type Substances 0.000 description 1
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Classifications
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- E—FIXED CONSTRUCTIONS
- E21—EARTH OR ROCK DRILLING; MINING
- E21B—EARTH OR ROCK DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
- E21B17/00—Drilling rods or pipes; Flexible drill strings; Kellies; Drill collars; Sucker rods; Cables; Casings; Tubings
- E21B17/02—Couplings; joints
- E21B17/04—Couplings; joints between rod or the like and bit or between rod and rod or the like
- E21B17/042—Threaded
- E21B17/0423—Threaded with plural threaded sections, e.g. with two-step threads
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- E—FIXED CONSTRUCTIONS
- E21—EARTH OR ROCK DRILLING; MINING
- E21B—EARTH OR ROCK DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
- E21B17/00—Drilling rods or pipes; Flexible drill strings; Kellies; Drill collars; Sucker rods; Cables; Casings; Tubings
- E21B17/02—Couplings; joints
- E21B17/08—Casing joints
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
- F16L—PIPES; JOINTS OR FITTINGS FOR PIPES; SUPPORTS FOR PIPES, CABLES OR PROTECTIVE TUBING; MEANS FOR THERMAL INSULATION IN GENERAL
- F16L15/00—Screw-threaded joints; Forms of screw-threads for such joints
- F16L15/001—Screw-threaded joints; Forms of screw-threads for such joints with conical threads
- F16L15/002—Screw-threaded joints; Forms of screw-threads for such joints with conical threads with more then one threaded section
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
- F16L—PIPES; JOINTS OR FITTINGS FOR PIPES; SUPPORTS FOR PIPES, CABLES OR PROTECTIVE TUBING; MEANS FOR THERMAL INSULATION IN GENERAL
- F16L15/00—Screw-threaded joints; Forms of screw-threads for such joints
- F16L15/006—Screw-threaded joints; Forms of screw-threads for such joints with straight threads
- F16L15/007—Screw-threaded joints; Forms of screw-threads for such joints with straight threads with more than one threaded section
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
- F16L—PIPES; JOINTS OR FITTINGS FOR PIPES; SUPPORTS FOR PIPES, CABLES OR PROTECTIVE TUBING; MEANS FOR THERMAL INSULATION IN GENERAL
- F16L15/00—Screw-threaded joints; Forms of screw-threads for such joints
- F16L15/04—Screw-threaded joints; Forms of screw-threads for such joints with additional sealings
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- Engineering & Computer Science (AREA)
- General Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- Mining & Mineral Resources (AREA)
- Life Sciences & Earth Sciences (AREA)
- Geology (AREA)
- Fluid Mechanics (AREA)
- Environmental & Geological Engineering (AREA)
- Physics & Mathematics (AREA)
- General Life Sciences & Earth Sciences (AREA)
- Geochemistry & Mineralogy (AREA)
- Non-Disconnectible Joints And Screw-Threaded Joints (AREA)
- Earth Drilling (AREA)
Abstract
Provided is a threaded joint for oil well steel pipes, which has excellent sealability and compression resistance. Comprising: a pin (2) provided with a male thread (4); and a box (3) provided with a female screw (5) screwed with the male screw (4), wherein the cross-sectional area S1 (mm) of the pin at a sealing point (sp1) at a predetermined position in the outer peripheral surface side sealing part (9)2) And the cross-sectional area S0 (mm) of the unprocessed portion (6) of the pin, i.e., the original tube portion2) Satisfies the formula: (S1/S0). times.100 ≧ 15 (%), and the cross-sectional area S2 (mm) of the tank at a seal point (sp2) at a predetermined position in the inner peripheral face side seal portion (10)2) And the cross-sectional area S0' (mm) of the unprocessed part (7) of the tank, i.e., the original pipe part2) Satisfies the formula: (S2/S0'). times.100. gtoreq.20 (%), and the cross-sectional area S3 (mm) of the contact portion (8) of the intermediate shoulder (C) between the thread rows (A, B)2) Cross-sectional area S0 (mm)2) Satisfies the formula: (S3/S0). times.100. gtoreq.10 (%).
Description
Technical Field
The present invention relates to a threaded joint for pipes used for oil country tubular goods including pipes and casings which are generally used in exploration or production of oil wells or gas wells. That is, the present invention relates to a threaded joint for pipes used for connecting steel pipes such as OCTG (oil country tubular goods), risers, and line pipes. The threaded joint for pipes of the present invention is excellent in sealability and compression resistance.
Background
Threaded pipe joints are widely used for connecting steel pipes used in oil production equipment such as oil country tubular goods. In the past, a threaded joint for pipes conforming to the standard specified by the API (american petroleum institute) standard has typically been used for the connection of steel pipes used for the search or production of oil or gas.
In recent years, wells for crude oil or natural gas have been increasingly deep, and horizontal wells, slant wells, and the like have been increased from vertical wells, and thus the excavation/production environment has become severer. Further, in the case where well development is increasing in severe environments such as oceans and polar regions, the performance required for a threaded joint varies in compression resistance, bending resistance, external pressure sealing performance, and the like. For such performance requirements, the use of high-performance special threaded joints for pipes called premium joints has been increasing in recent years.
In addition, in order to reduce the excavation amount in the well development, the well needs to be elongated. In contrast, among the above-described high-quality joints, there is an increasing demand for a pipe threaded joint of an integral type in which pipes are directly connected to each other without a connecting member.
The above-described premium joint is generally provided with a taper thread, a metal contact seal portion, and a torque shoulder portion on the pipe end side of each pipe. These are elements constituting a pin as a male portion provided on one end side of the pipe and a box as a female portion provided on one end side of the pipe and screwed or fitted to the male portion. These elements are designed so that the elements of the same name as the male and female elements face each other when the joint (meaning of a threaded pipe joint, the same hereinafter) is tightened.
The tapered threads described above are required in order to securely fix the joint. In addition, the metal contact seal portion ensures sealability by metal contact between the box and the pin in the region of the metal contact seal portion. The torque shoulder portion serves as a shoulder surface that functions as a stopper in fastening the joint.
In the integral type threaded joint for pipes (hereinafter, also referred to as an integral joint), the metal contact seal portions are provided at one or two or more locations in the axial direction (the axial direction). Wherein the metal contact seal portions of at least 1 portion are provided on an outer peripheral surface of a non-threaded portion (hereinafter, referred to as a nose) of the pin connected to a pin front end side threaded end of the tapered thread and an inner peripheral surface of a non-threaded portion (hereinafter, referred to as a nostril) of the box connected to a box rear end side threaded end of the tapered thread. When the metal contact seal portion is tightened, the metal contact seal portions of the nose and the nostril are in contact with each other in the radial direction, and a seal surface (for simplicity, referred to as an inner radial seal surface) which prevents fluid inside the pipe from entering a region of the tapered thread is formed.
In the integral joint, a region of the tapered thread is divided into two parts in the axial direction in each of the pin and the box. The thread row on the pin tip side and the thread row on the box rear side, which are screwed together, of the two divided parts are referred to as a first thread row. On the other hand, the screw row on the pin rear end side and the screw row on the box front end side to be screwed therewith are referred to as a second screw row. In the first and second screw rows, the first screw row is on the inner diameter side and the second screw row is on the outer diameter side in the radial direction (the meaning in the pipe diameter direction, the same applies hereinafter). The torque shoulder is provided at the boundary between the first thread row and the second thread row, and is referred to as an intermediate shoulder.
In the one-piece joint having the intermediate shoulder, when the metal contact seal portion is provided at two locations in the axial direction, one of the two locations forms the inner radial seal surface. The other metal contact seal portion is provided on an outer peripheral surface of the unthreaded portion of the pin connected to the rear end of the second thread row (referred to as a pin rear-end unthreaded surface for the sake of simplicity) and an inner peripheral surface of the unthreaded portion of the box connected to the front end of the second thread row (referred to as a box front-end unthreaded surface for the sake of simplicity). In the metal contact seal portion, when the joint is tightened, the metal contact seal portion of the pin rear-end-side unthreaded surface and the box front-end-side unthreaded surface radially contact each other, and a seal surface (for simplicity, referred to as an outer radial seal surface) that prevents fluid on the outside of the pipe from entering a region of the tapered thread is formed.
As an example of a conventional technique of a full body joint having the intermediate shoulder, a joint with a pipe thread (pipe threaded joint) described in patent document 1 is shown in fig. 3. The invention described in patent document 1 has an object to produce a threaded joint with a pipe provided with an improved seal while maintaining appropriate rigidity, and to improve resistance (characteristics) of the structure of the joint to high loads, particularly compressive loads, and to avoid the above characteristics from affecting the sealing function. In the invention described in patent document 1, a reinforcing portion protruding from the metal contact seal portion of the non-threaded surface on the box distal end side to the box distal end is provided, the length or thickness (wall thickness) of the reinforcing portion is determined, and the entire length of the reinforcing portion of the box is prevented from contacting the pipe (original pipe portion) on the pin rear end side facing the reinforcing portion.
Prior art documents
Patent document
Patent document 1: japanese patent No. 5232475
Problems to be solved by the invention
However, in the technique described in patent document 1, when a high load is applied to the combined load of the tension, compression, and further the internal pressure and the external pressure, it cannot be said that sufficient sealability is ensured, and improvement of sealability is desired. In addition, it is also required to improve the compression resistance together with the sealing property.
Disclosure of Invention
Accordingly, an object of the present invention is to provide a threaded joint for oil well steel pipes which is excellent in sealability and compression resistance.
In the present invention, the excellent sealing property means ISO 13679: the sealing performance evaluation test of the threaded joint under the combined load condition specified in the series a test of 2002 is passed.
In the present invention, the excellent compression resistance means that the sealability evaluation test is acceptable even when a high compression load is applied to any compression condition under the load conditions of the ISO test. The tensile load specifies 95% of the tensile strength of the pipe or joint as a maximum value, and the compression resistance is expressed as a ratio to the tensile load. In a T & C (threaded coupling) type joint, the strength of the joint is generally determined by the tensile strength of the pipe, and the performance of 80% or more compression ratio of the tensile strength of the pipe is referred to as high compressibility, and it can be said that the joint has very high compression resistance when 100% compression ratio can be achieved. In the half-flash type joint, the tensile strength is determined by the joint design, and 70% or more of the tensile strength of the pipe can be said to be a sufficient tensile strength design. In a half-flash type joint, the performance of the joint at 70% compression ratio or more of tensile strength is referred to as high compressibility, and when 100% compression ratio equivalent to tensile strength can be achieved, the joint is referred to as having very high compression resistance.
Means for solving the problems
The present inventors have made intensive studies to solve the above problems and have obtained the following findings. First, in the conventional technology, as a reason why the desired sealing property cannot be secured, attention is paid to a case where the rigidity of the pipe end side of the sealing portion is not sufficiently considered. The present inventors have also found that: by defining the cross-sectional area at a predetermined sealing point to ensure rigidity, sufficient surface pressure can be obtained even when a high load is applied, and sufficient sealing performance can be ensured. When a tensile force is applied, the diameter reduction deformation of the pin occurs simultaneously with the tensile deformation in a seal portion formed on the pipe end side of the box and formed by the contact between the box inner peripheral surface and the pin outer peripheral surface. Therefore, the amount of seal interference is reduced and the seal surface pressure of the pipe end side seal portion of the tank is reduced. That is, since the contact surface pressure of the pipe end side seal portion of the box is more likely to be reduced, it is also preferable to set the predetermined value of the seal cross-sectional area of the pipe end side seal portion of the box to be higher than the cross-sectional area of the pipe end side seal portion of the pin in order to ensure sealability. Further, it is also found that the compression resistance can be secured by defining the cross-sectional area ratio of the intermediate shoulder.
The gist of the present invention completed based on the above findings is as follows.
[1] A threaded joint for oil well steel pipes, comprising:
a pin, wherein one end of the steel pipe is provided with a male conical thread, namely a male thread; and
a box having a female screw as a female tapered screw to be screwed to the male screw, provided at one end of the steel pipe,
a radial seal structure for sealing fluid by bringing the pin into metal contact with the tank is provided at two locations, namely, an outer peripheral surface side seal portion on the tube end side of the pin and an inner peripheral surface side seal portion on the tube end side of the tank,
the threaded joint for oil well steel pipes has an intermediate shoulder formed in the middle of the thread row of the male and female tapered threads,
in the outer peripheral surface side seal portion formed on the tube end side of the pin, a cross-sectional area S1 (mm) of the pin at a seal point which is a portion on the outer peripheral surface of the nose portion on the pin side which first contacts the box side seal surface2) And the cross-sectional area S0 (mm) of the unprocessed portion of the pin, i.e., the original tube portion2) Satisfies the following formula (1),
a cross-sectional area S2 (mm) of the tank at a sealing point which is a portion on the inner peripheral surface of the pipe end portion on the tank side which is first brought into contact with the sealing surface on the pin side in the inner peripheral surface-side sealing portion formed on the pipe end side of the tank2) And the cross-sectional area S0' (mm) of the unprocessed part of the tank, i.e., the original pipe part2) Satisfies the following formula (2),
area S3 (mm) of the contact portion of the intermediate shoulder2) And the cross-sectional area S0 (mm) of the unprocessed portion of the pin, i.e., the original tube portion2) Satisfies the following formula (3).
(S1/S0)×100≥15(％)…(1)
(S2/S0’)×100≥20(％)…(2)
(S3/S0)×100≥10(％)…(3)
[2] The threaded joint for oil well steel pipes according to item [1], wherein,
the S1, the S0, the S2, and the S0' satisfy the following formula (4).
(S1/S0)≤(S2/S0’)…(4)
Effects of the invention
According to the present invention, a threaded joint for oil well steel pipes excellent in sealability and compression resistance can be obtained.
Drawings
Fig. 1 is a cross-sectional view of a threaded joint for an oil country tubular good illustrating an example of an embodiment of the present invention, and is also an illustrative view of equations (1) and (3).
Fig. 2 is a cross-sectional view of a threaded joint for an oil country tubular good illustrating an example of the embodiment of the present invention, and is also an explanatory view of equation (2).
Fig. 3 is a cross-sectional view showing an example of a conventional threaded joint for oil country tubular goods, wherein (a) is a cross-sectional view in the axial direction of the pipe, and (b) is an enlarged cross-sectional view showing a metal contact seal portion.
Description of the reference symbols
Threaded joint for oily steel pipe
2 Pin
3 case
4 male thread
5 female thread
6-pin unprocessed portion
7 case unprocessed portion
8 contact part
9 outer peripheral surface side seal part
10 inner peripheral side seal part
11. 12 shoulder part
A first thread row
B second thread row
C middle shoulder
sp1 sealing point
sp2 sealing point
Alpha screw joint shaft
Detailed Description
The present invention will be described below with reference to the accompanying drawings. Fig. 1 is a cross-sectional view of a threaded joint for an oil country tubular good illustrating an example of an embodiment of the present invention, and is also an explanatory view of equations (1) and (3) described below. Fig. 2 is a cross-sectional view of a threaded joint for an oil country tubular good illustrating an example of the embodiment of the present invention, and is also an explanatory view of the following expression (2). Fig. 3 is a cross-sectional view showing an example of a conventional threaded joint for an oil country tubular good, where (a) is a cross-sectional view in the axial direction of the pipe, and (b) is an enlarged cross-sectional view showing a metal contact seal portion.
In the threaded joint 1 for oil well steel pipes of the present invention, steel pipes are connected by a pin 2 and a box 3. As shown in fig. 1 and 2, a threaded joint 1 for an oil country tubular good according to the present invention is a threaded joint (premium joint) formed by screwing a pin 2 and a box 3 together. Further, the threaded joint 1 for oil well steel pipes of the present invention is an integral type threaded joint in which steel pipes are directly connected to each other by a pin 2 and a box 3.
A male tapered thread, i.e., a male thread 4, is provided at one end of the steel pipe of the pin 2. A female screw 5, which is a female tapered screw to be screwed into the male screw 4, is provided at one end of the steel pipe of the tank 3.
In the threaded joint 1 for an oil country tubular good according to the present invention, a radial seal structure in which a pin 2 and a box 3 are in metal contact to seal a fluid is provided at two locations, an outer peripheral surface side seal portion 9 on the pipe end side of a male thread 4 (the negative direction side of an X axis parallel to a threaded joint axis α in fig. 1 and 2) and an inner peripheral surface side seal portion 10 on the pipe end side of a female thread 5 (the positive direction side of the X axis in fig. 1 and 2). The outer circumferential side seal portion 9 and the inner circumferential side seal portion 10 may be metal contact seal portions as described with reference to fig. 3.
When the joint is tightened, the outer peripheral side seal portion 9 can form a seal surface that prevents fluid inside the pipe from entering the region of the tapered thread by bringing the metal contact seal portions of the nose (the unthreaded portion of the pin 2 connected to the pin front end side threaded end of the tapered thread) and the nostril (the unthreaded portion of the box 3 connected to the box rear end side threaded end of the tapered thread) into contact with each other.
The inner peripheral side seal portion 10 is provided on an outer peripheral surface of a non-threaded portion (for simplicity, referred to as a pin rear side non-threaded surface) of the pin 2 connected to the rear end of the second thread row B and an inner peripheral surface of a non-threaded portion (for simplicity, referred to as a box front side non-threaded surface) of the box 3 connected to the front end of the second thread row B. The inner peripheral side seal portion 10 forms a seal surface that prevents fluid outside the pipe from entering a region of the tapered thread by the contact between the pin rear end side non-threaded surface and the box front end side non-threaded surface at the time of fastening the joint.
The threaded joint 1 for an oil country tubular good according to the present invention has an intermediate shoulder C formed in the middle of 2 thread rows (first thread row a and second thread row B) of the male and female tapered threads. The intermediate shoulder C functions as a torque shoulder serving as a shoulder surface functioning as a stopper in fastening of the joint.
The threaded joint 1 for an oil country tubular good according to the present invention may have a shoulder 11 at the tip of the pin 2, or may have a shoulder 12 in contact with the shoulder 11 provided on the box 3.
Further, the threaded joint 1 for oil well steel pipe of the present invention is characterizedThe first is the cross-sectional area S1 (mm) of the pin at the seal point sp1 (see fig. 1) which is the portion of the outer peripheral surface of the nose portion on the pin 2 side that first comes into contact with the seal surface on the box 3 side in the outer peripheral surface side seal 92) And a cross-sectional area S0 (mm) of the original tube part as the unprocessed portion 6 of the pin2) Satisfies the following formula (1). The raw pipe portion (the pin unprocessed portion 6) is a region other than the male thread provided at the tip of the pin 2, and has a cylindrical shape.
(S1/S0)×100≥15(％)…(1)
If "(S1/S0) × 100" is less than 15%, leakage occurs due to stretching and internal pressure, and sufficient sealability cannot be ensured. Therefore, in the present invention, "(S1/S0). times.100" is set to 15% or more, preferably 20% or more. More preferably 25% or more. On the other hand, in the present invention, if "(S1/S0) × 100" is set to exceed 50%, the cross-sectional area of the intermediate shoulder C and the outer peripheral surface side seal portion 9 cannot be secured, and sufficient performance may not be obtained. Therefore, in the present invention, "(S1/S0). times.100" is preferably set to 50% or less. More preferably 40% or less.
The cross sections of the cross-sectional areas S1 and S0 are cross sections of a plane perpendicular to the threaded joint axis α (positive and negative X-axis direction), and the cross sections of the cross-sectional areas S2 and S3 described below are also cross sections of a plane perpendicular to the threaded joint axis α (positive and negative X-axis direction).
The above-mentioned "side of the pin 2 which first contacts the sealing surface on the case 3 side" means the foremost end position (foremost end position on the X-axis negative direction side) of the pin 2 which contacts the sealing surface on the case 3 side.
In the threaded joint 1 for oil country tubular goods according to the present invention, the cross-sectional area S2 (mm) of the box 3 at the sealing point sp2 (see fig. 2), which is the portion on the inner peripheral surface of the end of the box 3 on the side that first contacts the sealing surface on the pin 2 side, is also characteristic of the outer surface side seal 102) And the cross-sectional area S0' (mm) of the unprocessed part 7 of the tank, i.e., the original pipe part2) Satisfies the following formula (2). The raw pipe portion (tank unprocessed portion 7) is a region other than the female screw provided at the distal end of the tank 3, and has a cylindrical shape.
(S2/S0’)×100≥20(％)…(2)
If "(S2/S0'). times.100" is less than 20%, leakage occurs due to tension and external pressure, and sufficient sealing properties cannot be secured. Therefore, in the present invention, "(S2/S0'). times.100" is set to 20% or more, preferably 25% or more. More preferably 30% or more. On the other hand, in the present invention, if "(S2/S0') × 100" exceeds 50%, it is difficult to secure the cross-sectional areas of the inner peripheral side seal portion 10 and the intermediate shoulder C, and sufficient performance may not be obtained. Although it is not impossible to increase the outer diameter of the inner peripheral surface side seal portion to achieve a high cross-sectional area, the case of increasing the outer diameter is contrary to the implementation of a slender joint that is a feature of an integral threaded joint, and therefore, a design with an excessively large outer diameter is not practical. Therefore, in the present invention, "(S2/S0'). times.100" is preferably 50% or less. More preferably 45% or less.
The above-mentioned "case 3 side which first contacts the seal surface on the pin 2 side" means the foremost end position (foremost end position on the X-axis positive direction side) of the case 3 which contacts the seal surface on the pin 2 side.
The threaded joint 1 for oil country tubular goods according to the present invention is also characterized in that the area S3 (mm) of the contact portion 8 (see fig. 1) of the intermediate shoulder C2) And the cross-sectional area S0 (mm) of the unprocessed pin part 6, i.e., the original tube part2) Satisfies the following formula (3).
(S3/S0)×100≥10(％)…(3)
If "(S3/S0) × 100" is less than 10%, an excessive load acts on the seal portion during compression, which causes a decrease in sealability due to plastic deformation, and leakage due to tension and internal pressure occurs, and sufficient sealability cannot be ensured. In addition, during fastening, plastic deformation may occur in the shoulder portion, and fastening may not be possible. Therefore, in the present invention, "(S3/S0). times.100" is set to 10% or more, preferably 15% or more. More preferably 20% or more. On the other hand, in the present invention, if "(S3/S0) × 100" exceeds 50%, the cross-sectional areas of the outer circumferential side seal part 9 and the inner circumferential side seal part 10 cannot be secured, and sufficient performance may not be obtained. Therefore, "(S3/S0). times.100" is preferably 50% or less in the present invention. More preferably 40% or less.
In the present invention, the desired sealing property and compression resistance can be obtained by satisfying all of the above-described expressions (1) to (3).
In addition, in the threaded joint 1 for oil well steel pipes according to the present invention, it is preferable that S1, S0, S2, and S0' described above satisfy the following formula (4).
(S1/S0)≤(S2/S0’)…(4)
When a tensile force acts on the joint, deformation on the diameter reduction side occurs simultaneously with deformation on the tensile side. Therefore, the amount of seal interference decreases, and the seal surface pressure of the inner peripheral surface side seal portion 10 formed on the tube end side of the tank decreases. That is, since the contact surface pressure of the inner peripheral side sealing portion 10 is more likely to be reduced, it is preferable to set the predetermined value of the sealing cross-sectional area of the inner peripheral side sealing portion 10 higher than that of the outer peripheral side sealing portion 9 in order to ensure the sealing property. Therefore, in the present invention, by setting (S2/S0') to (S1/S0) or more, that is, by setting the sealing cross-sectional area ratio of the inner peripheral side sealing portion 10 to be higher than the sealing cross-sectional area ratio of the outer peripheral side sealing portion 9, more sufficient sealing performance can be ensured. Therefore, in the present invention, "(S1/S0) ≦ (S2/S0 ')" is preferably used, and (S2/S0') is more preferably 1.1 times or more as large as (S1/S0). More preferably 1.2 times or more.
In the present invention, although not particularly limited, the outer diameters of the pin unprocessed portion 6 and the box unprocessed portion 7 are preferably 5 to 16 inches, and more preferably 5.5 to 14 inches.
In the present invention, the thickness of the pin unprocessed portion 6 and the box unprocessed portion 7 is preferably 12mm or more, and more preferably 15mm or more.
In the threaded joint of the present invention, the angle of the load flank is preferably 5 to 30 degrees, and more preferably 10 to 25 degrees.
In addition, the angle of the lateral surface of the inserted tooth is preferably-10 to 0 degrees, and more preferably-7 to-3 degrees.
As described above, according to the present invention, a threaded joint for oil well steel pipes excellent in sealability and compression resistance can be obtained.
Examples
The present invention will be described below based on examples.
Samples were produced for a threaded joint comprising a pin formed by machining the end of a steel pipe of API 5CT steel type Q125 having an outer diameter of 9 to 5/8 inches × a wall thickness of 0.545 inches (outer diameter 244.48mm × wall thickness 13.84mm) and a box corresponding to the pin, and ISO 13679: 2002. In this example, experiments were performed under the experimental conditions of the respective levels shown in table 1. In addition, as experimental conditions not shown in table 1, the angle of the load flank was set to-5 degrees and the angle of the stabbing flank was set to 15 degrees as the thread contact surface in common at all levels.
In table 1, the area ratio (%) of the outer peripheral surface side seal portion to the unprocessed portion of the female pipe means "the cross-sectional area S1 (mm) of the pin at the seal point which is the portion on the outer peripheral surface of the nose portion on the pin side which first contacts the seal surface on the box side, that is, the portion on the outer peripheral surface of the nose portion on the pin side2) Cross-sectional area S0 (mm) of the unprocessed portion of the pin, i.e., the original tube portion2) (S1/S0). times.100 [% ]])”。
The area ratio (%) of the inner peripheral side seal portion to the unprocessed portion of the female pipe means "the cross-sectional area S2 (mm) of the tank at the seal point which is the portion on the inner peripheral surface of the pipe end portion on the tank side which first comes into contact with the seal surface on the pin side, i.e., the portion on the inner peripheral surface of the pipe end portion on the tank side2) Cross-sectional area S0' (mm) of unprocessed part of tank, i.e. original pipe part2) Ratio of ((S2/S0'). times.100 [% ]])”。
The area ratio (%) of the intermediate shoulder to the unprocessed portion of the parent tube means "the area S3 (mm) of the contact portion of the intermediate shoulder2) Cross-sectional area S0 (mm) of the unprocessed portion of the pin, i.e., the original tube portion2) (S3/S0). times.100 [% ]])”。
The test of this example is a test for evaluating sealability by applying a composite load of tensile/compressive force and internal/external pressure as loads in the series a test, and the load schedule is defined by VME 95% and API Collapse pressure. In this test, the maximum tensile rate of the test was 70%.
When the test passed the sealing test under a load condition of a maximum compression ratio of 49% (70% in terms of a ratio to a tensile ratio), the sealing property and the compression resistance were both excellent, and the performance was evaluated as passed. The design is more excellent in compression resistance when passing a sealing test under a load condition of 70% of the maximum compression ratio (100% in terms of the ratio to the elongation).
The results are shown in Table 1.
[ Table 1]
As shown in table 1, in comparative example 1, since the area ratio of the intermediate shoulder was extremely small, plastic deformation occurred in the shoulder portion at the time of fastening, and the intermediate shoulder became defective at the time of fastening.
In comparative example 2, since the area ratio of the intermediate shoulder is less than 10%, an excessive load acts on the seal portion during compression, which causes a decrease in sealability due to plastic deformation, and a leak occurs due to tension and internal pressure (hereinafter, also referred to as tension + internal pressure), resulting in a failure.
In comparative example 3, the area ratio of the outer peripheral surface side seal portion was less than 15%, and therefore, leakage occurred under the stretching + internal pressure, and this became a failure.
In comparative example 4, the area ratio of the inner peripheral side seal portion was less than 20%, and therefore, leakage was caused by stretching and external pressure (stretching + external pressure), and the result was a failure.
On the other hand, the examples 1 to 5 of the present invention were all acceptable, and it was found that the examples of the present invention have excellent sealing properties and compression resistance.
Claims (2)
1. A threaded joint for oil well steel pipes, comprising:
a pin, wherein one end of the steel pipe is provided with a male conical thread, namely a male thread; and
a box having a female screw as a female tapered screw to be screwed to the male screw, provided at one end of the steel pipe,
a radial seal structure for sealing fluid by bringing the pin into metal contact with the tank is provided at two locations, namely, an outer peripheral surface side seal portion on the tube end side of the pin and an inner peripheral surface side seal portion on the tube end side of the tank,
the threaded joint for oil well steel pipes has an intermediate shoulder formed in the middle of the thread row of the male and female tapered threads,
in the outer peripheral surface side seal portion formed on the tube end side of the pin, a cross-sectional area S1 (mm) of the pin at a seal point which is a portion on the outer peripheral surface of the nose portion on the pin side which first contacts the box side seal surface2) And the cross-sectional area S0 (mm) of the unprocessed portion of the pin, i.e., the original tube portion2) Satisfies the following formula (1),
a cross-sectional area S2 (mm) of the tank at a sealing point which is a portion on the inner peripheral surface of the pipe end portion on the tank side which is first brought into contact with the sealing surface on the pin side in the inner peripheral surface-side sealing portion formed on the pipe end side of the tank2) And the cross-sectional area S0' (mm) of the unprocessed part of the tank, i.e., the original pipe part2) Satisfies the following formula (2),
area S3 (mm) of the contact portion of the intermediate shoulder2) And the cross-sectional area S0 (mm) of the unprocessed portion of the pin, i.e., the original tube portion2) Satisfies the following formula (3),
15≤(S1/S0)×100≤30…(1)
20≤(S2/S0’)×100≤50…(2)
10≤(S3/S0)×100≤35…(3)。
2. the threaded joint for oil well steel pipes according to claim 1,
the S1, the S0, the S2 and the S0' satisfy the following formula (4),
(S1/S0)≤(S2/S0’)…(4)。
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2016193707 | 2016-09-30 | ||
| JP2016-193707 | 2016-09-30 |
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| Publication Number | Publication Date |
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| CN107883082A CN107883082A (en) | 2018-04-06 |
| CN107883082B true CN107883082B (en) | 2020-10-30 |
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| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN201721253688.XU Active CN207394154U (en) | 2016-09-30 | 2017-09-27 | Oil well steel pipe nipple |
| CN201710890006.4A Active CN107883082B (en) | 2016-09-30 | 2017-09-27 | Threaded joint for oil well steel pipe |
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| Application Number | Title | Priority Date | Filing Date |
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| CN201721253688.XU Active CN207394154U (en) | 2016-09-30 | 2017-09-27 | Oil well steel pipe nipple |
Country Status (14)
| Country | Link |
|---|---|
| US (1) | US11053749B2 (en) |
| EP (1) | EP3486540B1 (en) |
| JP (1) | JP6519030B2 (en) |
| CN (2) | CN207394154U (en) |
| AR (1) | AR109767A1 (en) |
| AU (1) | AU2017338057C1 (en) |
| BR (1) | BR112019004059B1 (en) |
| CA (1) | CA3031919C (en) |
| ES (1) | ES2858456T3 (en) |
| MX (1) | MX2019002351A (en) |
| MY (1) | MY196098A (en) |
| RU (1) | RU2712651C1 (en) |
| SA (1) | SA519401174B1 (en) |
| WO (1) | WO2018061767A1 (en) |
Families Citing this family (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| MX2019002351A (en) | 2016-09-30 | 2019-05-30 | Jfe Steel Corp | Threaded joint for oil well steel pipe. |
| EP3572612B1 (en) * | 2018-05-25 | 2020-10-07 | Vallourec Oil And Gas France | Tubular threaded connection |
| EP3572611B1 (en) * | 2018-05-25 | 2020-12-30 | Vallourec Oil And Gas France | Tubular threaded connection |
| CN113227626B (en) * | 2018-12-25 | 2022-11-29 | 日本制铁株式会社 | Threaded joint for steel pipe |
| FR3098878B1 (en) * | 2019-07-19 | 2021-07-30 | Vallourec Oil & Gas France | Threaded joint for oil well casing column |
| PL3798409T3 (en) * | 2019-09-24 | 2023-12-04 | Vallourec Oil And Gas France | Threaded connection including an intermediate shoulder |
| CN112576200B (en) * | 2019-09-27 | 2023-03-14 | 宝山钢铁股份有限公司 | Steel pipe air-tight seal structure with inner liner |
| US20240183228A1 (en) * | 2022-12-06 | 2024-06-06 | Saudi Arabian Oil Company | Threaded and Coupled Connection |
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- 2017-09-13 BR BR112019004059-5A patent/BR112019004059B1/en active IP Right Grant
- 2017-09-13 WO PCT/JP2017/033006 patent/WO2018061767A1/en active Application Filing
- 2017-09-13 EP EP17855723.7A patent/EP3486540B1/en active Active
- 2017-09-13 ES ES17855723T patent/ES2858456T3/en active Active
- 2017-09-13 JP JP2017562105A patent/JP6519030B2/en active Active
- 2017-09-13 MY MYPI2019000456A patent/MY196098A/en unknown
- 2017-09-13 AU AU2017338057A patent/AU2017338057C1/en active Active
- 2017-09-13 RU RU2019105594A patent/RU2712651C1/en active
- 2017-09-13 CA CA3031919A patent/CA3031919C/en active Active
- 2017-09-13 US US16/328,006 patent/US11053749B2/en active Active
- 2017-09-27 CN CN201721253688.XU patent/CN207394154U/en active Active
- 2017-09-27 CN CN201710890006.4A patent/CN107883082B/en active Active
- 2017-09-29 AR ARP170102723A patent/AR109767A1/en active IP Right Grant
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2019
- 2019-02-24 SA SA519401174A patent/SA519401174B1/en unknown
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| CN1155639A (en) * | 1995-10-03 | 1997-07-30 | 瓦卢雷石油和气体公司 | Threaded joint for tubes |
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Also Published As
| Publication number | Publication date |
|---|---|
| SA519401174B1 (en) | 2022-03-16 |
| BR112019004059B1 (en) | 2022-10-04 |
| CA3031919A1 (en) | 2018-04-05 |
| EP3486540B1 (en) | 2021-01-13 |
| US20190211632A1 (en) | 2019-07-11 |
| JPWO2018061767A1 (en) | 2018-10-04 |
| MX2019002351A (en) | 2019-05-30 |
| MY196098A (en) | 2023-03-14 |
| AU2017338057B2 (en) | 2020-04-09 |
| CN207394154U (en) | 2018-05-22 |
| CA3031919C (en) | 2021-02-02 |
| AU2017338057C1 (en) | 2020-07-16 |
| CN107883082A (en) | 2018-04-06 |
| ES2858456T3 (en) | 2021-09-30 |
| AR109767A1 (en) | 2019-01-23 |
| EP3486540A1 (en) | 2019-05-22 |
| WO2018061767A1 (en) | 2018-04-05 |
| BR112019004059A2 (en) | 2019-05-28 |
| EP3486540A4 (en) | 2019-07-24 |
| US11053749B2 (en) | 2021-07-06 |
| JP6519030B2 (en) | 2019-05-29 |
| AU2017338057A1 (en) | 2019-02-14 |
| RU2712651C1 (en) | 2020-01-30 |
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